In the oil and gas industry, a common problem in drilling operations is the loss of valuable drilling fluids into fractures induced by excessive mud pressure, preexisting open porosity/fractures or large caverns in the formation.
One of the methods to prevent loss event from happening or stop the loss is via addition of granular particles into the drilling fluid, which act as bridging agent to establish the foundation for complete sealing of the fracture or as wellbore strengthening materials that pop the fracture open. Such materials include graphite, petroleum coke, walnut shell, calcium carbonate, among others.
Superior Graphite Co. introduced resilient graphitic carbon for use as an LCM in the 1990s (see, U.S. Pat. No. 5,826,669, incorporated herein by reference). The resilient graphite is believed capable of packing tightly under compression in the pores and fractures, to expand or contract without being dislodged or collapsed due to changes in the equivalent circulating density or with an increase in fluid weight. In addition, graphite also worked as solid lubricant to reduce wear of metal components and improve drilling efficiency. The graphitic materials described in the '669 patent have a resiliency/rebound higher than 35% upon compression at 10,000 psi, with particle density from 1.45-2.2 gram/cc. Such an RGC material for use as an LCM is commercially available under the trade name STEELSEAL® from Halliburton Inc. The STEELSEAL® additive is manufactured by Superior Graphite Co and is considered as standard practice of U.S. Pat. No. 5,826,669. While such resilient graphitic carbon materials have provide superior LC control, improvement in performance is desirable.